There are three SIM card sizes
|SIM Type||Alternative Name||Length (mm)||Width (mm)||Height (mm)|
|Standard SIM||2FF or “Mini SIM”||25.00||15.00||0.76|
Most phones sold in the last few years use micro or nano. Standard SIM are pretty obsolete these days, more than likely you will not use it.
Here is a graphic, if it looks like the below, you can match up the size.
You can always cut a larger sim card to a smaller size. Or you can insert a smaller sim card into a larger compartment, use tape or another adhesive to make sure the metal is in contact.